IP 476: Petroleum liquids - Automatic pipeline sampling

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Method adopted/last revised: 2002

Method reapproved: None

REF/ISBN: IP476-2934869

Status: Current

First printed in STM books: January 2002

Scope

This International Standard recommends procedures to be used for obtaining,
by automatic means, representative samples of crude oil and liquid petroleum
products being conveyed by pipeline.

NOTE - Although throughout this
international Standard the term crude oil is used, this should be taken to
include other petroleum liquids where the technique and equipment are also
applicable.

This International Standard does not apply to the sampling of
liquefied petroleum gases and liquefied natural gases.

The principal purpose
of this International Standard is to give guidelines for specifying, testing,
operating, maintaining and monitoring crude oil samplers.

The sampling
procedures for crude oil are intended to provide representative samples for the
determination of a) the oil composition and quality; b) the total water
content; c) other contaminants that are not considered to be part of the
crude oil transferred.

If the sampling procedures for a), b) and c) are in
conflict, separate samples may be required.

NOTE - The results of the
laboratory analysis may be used for calculating adjustments to the declared
quantity of crude oil transferred. The procedure for carrying out the
adjustments does not form part of this International Standard.

Sample
handling is included, covering all aspects following collection to the transfer
of the sample to laboratory apparatus.

This International Standard describes
the practices and procedures believed at the present time to be the most likely
to lead to representative sampling and hence to accurate water determination.
However, the accuracy of the water determination on pipeline samples obtained
using automatic samplers will depend upon the arrangement and characteristics of
all the various elements making up the sampling system, and on the accuracy of
the subsequent analytical procedures.

A theoretical technique for evaluating
the combined accuracy of the automatic sampling system and the analytical test
is given in clause 16. A practical test procedure for field use is described in
clause 15.

Normally, the acceptable accuracy limits for a particular
automatic sampling system will be specified in agreement between the interested
parties.

Table 4 of clause 15 classifies the performance of automatic
sampling systems by ratings based on the accuracy of practical test results.
These ratings may be used as a guide to possible performance and as a basis for
individual agreement.

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